Transcript for Alleged murder-for-hire plot led to Texas veterinarian's suicide

I hate the idea they think I'm a monster. Reporter: Monster, not a word Valerie Mcdaniel easily friends would use to describe her. Valerie was an amazing human being. She had a light within her. Reporter: And an alleged murder for hire plot about the last thing they thought she'd ever be involved in. I wanted to take time and tell my story from the beginning. Try not to judge me. Reporter: These audio diaries a window into a life unraveling. By all accounts, everything seemed picture perfect. A loving mother living in river oaks, an affluent neighborhood in Houston, a condo in this fancy high rise. And running a thriving veterinary clinic. She was so successful and so beautiful and funny and intelligent. Reporter: But privately, Valerie's struggling to rebuild from a failed marriage. She did not feel loved. Reporter: Until, that is, she meets this man, Leon Jacob, a brash doctor eight years her junior. I was lonely. And he kept me company. He listened to me. He was everything I needed. Reporter: In her words, Valerie fell deeply in love. Leon can be charming and disarming, just ask him. It seems like you're a svengali, with a flick of a finger making this woman fall madly in love with you. Without sounding like a pompous ass, I can only describe it as, I've always understood women really well and they've always liked me. Reporter: But it's the back end of some of Leon's relationships that have been problematic. His first marriage ended in divorce, followed by charges of aggravated stalking and intimidation. Attempted cyber harassment is what I pled guilty to. She went a little overboard with her complaints about about me. Reporter: But his romantic troubles continued. The police were called to the scene of an alleged fight he had with a woman he was dating named Megan back in January. According to the police report you busted her lip. Okay, that's true -- You put a hand on her. I never put a hand on her. Subsequently that charge was dropped because there was no evidence. Reporter: Cops charge Leon was stalking her. Ex-girlfriend says that he hides in the bushes and waits outside her workplace. They caught you loitering outside her office, she says in the bushes -- She says that. You can claim a lot of things, right? You can say, you know, Superman came and took toe am krypton for the weekend, doesn't make it true. Reporter: Megan's gone but the stalking charge lingers. A felony conviction could keep him from ever getting his medical license. According to prosecutors, the way he's going to eliminate that problem is by eliminating her. Reporter: Investigators say that's what leads Leon to this guy, a former army sergeant and purple heart recipient who calls himself Zach. These days Zach is bringing new meaning to the term "Soldier of fortune." Cops say Zach promises to take care of Leon's problem for a price. $5,000 in cash, two Cartier watches, and a laptop. But according to investigators, Zach takes the money and runs without ever firing a single shot. Eventually the cops find out about the alleged plot and Zach ends up working with them. Zach tells us that Mr. Jacob has hired him to kill the victim in this case. Reporter: Prosecutors say that with police secretly listening in, Zach calls and informs Leon he's outsourced the job. They have Zach call Leon and say, hey, I got a guy, he's going to do the hit for us. Reporter: But that new guy is actually an undercover cop named Javier. We've been asked now to show his face. I was shocked that Leon wanted two people killed. And that his girlfriend, Valerie, would also be involved. Reporter: His girlfriend, Valerie. The vet and new love in his life. And that second person they allegedly want whacked? Her exhusband, Mack. At that point they decide to meet at Olive Garden. They were sitting at this table? Yes. Reporter: At this very table the vet, Valerie. Leon, and Zach and you've yes, sir posing as a contract killer. Cops say hee onmade his target clear. He told me on more than one occasions that his survival is more important than hers. Reporter: As Leon and Zach take a cigarette break, cops say the undercover Javier and Valerie are left alone to discuss intended target number two. Valerie's ex, Mack. She said, I have no other choice, he's going to take my baby from me. And he finally gets her to say that she does in fact want him to be killed. Reporter: Police spring into action, immediately reaching out to Valerie's ex-husband, Mack, to tip him off. We've recreated the scene to show how the cops enlisted Mack to stage his own death. They do a series of pictures of him dead. Reporter: He agrees to pose for photos like these, complete with a bullet wound to his head. Megan also agrees to assist in the sting, staging her own set of pictures, like these, to make it look like she'd been kidnapped. Leon kept using the word "Disappear, or he would say, I want her gone, I want her to go away forever. And I took that to understand that he wanted her dead. Reporter: The cops are now ready to take their next step. Informing Leon and Valerie that Mack has been killed. Javier fill posing as that hitman. I begin to tell Valerie and Leon that Mack was gone. That it was done. Leon gives me the cash, and I count out $1,800. Reporter: Later that same day, Javier says he informs Leon that the other job is done too. Megan is now a memory. So at that point, we close body cases. But we decided we wanted to go an extra step. So that extra step was the death notice. Reporter: A death notice. Now that's what cops call it when they have to notify next of kin that a loved one has passed. So now it's these police officers who have to give a performance. Can we talk to you, please? Yeah, come in, what's going on? Reporter: It's all being recorded as potential evidence on police body cameras. I'm afraid we have some bad news. Your ex-husband's been found. It looks like it turns out to be a fatality. Looks like it might have been robbery gone wrong. Sorry to have to tell you. Have you heard from him recently? I heard from him last night. Reporter: Soon enough Leon emerges from the bedroom. Her ex-husband's been found tonight. Oh my god. It looks like it might have been a robbery gone wrong. Oh my . Wanted to see if anybody knows anything or -- No. Might be able to help us? Reporter: Listen carefully to what Leon says next. Cops say it's sounding like he's establishing his whereabouts. We've been here all night. We were here all day with their daughter, watching movies. Reporter: Now police believe they have enough evidence to end the masquerade. All right, I'll tell you we'll need you to come with us and -- Oh, so I guess I'll stay. Okay, what, right now we're going to read you your rights. Me? Both of you are being arrested for solicitation of capital murder. Solicitation of murder. Reporter: There's another surprise in store for valle. As she's being hauled off to jail, someone's waiting side her front door. It's her ex-husband, Mack, back from the dead, waiting to take custody of their young daughter. I wonder what was going through her mind at that moment. That she handed her over to the man she tried to murder. Both of you are being arrested. Reporter: The two are charged with allegedly hiring a hitman to kill both their exes. Nothing to state, your honor. No judge, thank you. Reporter: Four days later Valerie released on a $50,000 bond. But just two weeks later, she took her own life. I didn't wake up one day and just say, hey, I want to kill my ex-husband. Things just gradually happened. Reporter: Valerie's former lover, Leon Jacob, has been sitting in the Harris county jail for almost seven months. He's awaiting trial on charges of stalking and solicitation of murder. When I sat down with him, he wouldn't talk about the details of his case. But denied any wrongdoing. I am innocent of these charges. I still maintain that throughout. Did you hold yourself responsible for her suicide? No. That was a decision she made on her own. She had so much pressure on her, and I wasn't there to help support her. Reporter: Prominent defense attorney George parnum is representing Leon. Do you know of any recordingings? Reporter: He gave us a preview of defense strategy, accusing police of entrapment. They were active players in this whole solicitation of capital murder. Reporter: Leon's in this pick pickle, according to parnum, because of Valerie. Valerie was extremely instrumental in a fact situation that lands my client in jail, behind bars. Reporter: But Leon says his feelings for Valerie haven't changed. And I did love her. I still do. Very, very much. Reporter: He has pleaded not guilty to all charges. But if convicted, Leon Jacob could face life in prison. He is scheduled to go to trial in December. For "Nightline," I'm Matt Gutman in Houston.

This transcript has been automatically generated and may not be 100% accurate.

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